INTRODUCTION

A - In its normal state

   The heart is a pump essentially constituted of a hallow muscle (the myocardium) the regular contractions of which enable the blood to circulate through the body.

The right ventricule draws the blood full of carbon dioxide and low in oxygen, and pumps it towards the lungs where respiratory exchanges tacke place (evacuation of carbon dioxide, renewal of oxygen supply).

The left ventricule receives the blood from the lungs and propels in throughout the organism through the aorta and the other arteries. A complex set of valves directs this flow through the different cardiac cavities. To carry out this work, the heart needs energy which is provided in the form of oxygen contained in the blood.

Coronary arteries maintain blood circulation inside the cardiac muscle itself.

Two mains coronarys arteries starting at the root of the aorta can be distinguished :

• The left coronary artery (LCA) splits into two branches after a left main :

  • the left anterior descending artery (LAO) and its diagonal branches.

  • the left circonflex artery and its marginal branches.

• The right coronary artery and its posterior descending arteries and posterial left ventricular arteries.